There is no 16th airborne brigade in the Russian armed forces, and no Russian airborne brigades are stationed in Russia's Orenburg region.
"An armed man guarding the facility at one of the sites claimed that he and those present at the site were part of the 16th airborne brigade from Orenburg, Russian Federation. They did not wear identifying insignia," the OSCE report said.
The OSCE, which strives to monitor the conflict impartially, noted down the man's statement in the monitoring mission report.
"The reliability of these statements must be checked," the Kremlin's spokesman Dmitry Peskov said in response to a question on the issue.
The unidentified man's claim has been circulated in Ukrainian media as an argument for the presence of Russian troops in Ukraine. Ukrainian President Petro Poroshenko has previously claimed that over 9,000 Russian troops are present in Ukraine, although he did not specify how they had been identified.